The present invention relates to a device for separating continuously fed products into groups, applicable in particular to machines for packaging groups of bottles or cans in shrink film, stretch film, cardboard, etc.
In the art field embracing automatic machines of the type in question, the packaging line (of which the function is first to define and select a group of products and then to wrap the group, according to various criteria) includes a feed station from which bottles are supplied continuously to the line (reference is made in the present specification to bottles, albeit the invention is applicable equally to other types of containers, namely cans, jars and the like), located upstream of the machine relative to a feed path along which the bottles are caused to advance.
The bottles advance on a horizontal conveyor belt one behind another, ordered in columns of given width, toward an intermediate separating station that serves to establish the size of the groups of bottles being wrapped (or, the number of bottles per group) and comprises a second conveyor belt, likewise horizontal. The selected group of bottles then passes to a station where it is wrapped in a sheet of plastic film, preferably heat-shrinkable.
To ensure the bottles are divided up correctly into groups, the separating station is equipped by way of example with a first barrier (as in Italian patent application BO93A 000428) rendered capable of reciprocating movement in a vertical direction and positioned at the downstream end of the feed station, by which the bottles can be checked or allowed through to an intermediate pre-separating station located between the feed station and the separating station proper. The intermediate station is equipped in turn with a second vertical barrier located at a distance from the first barrier equal to the corresponding dimension of the group of bottles being selected, and positionable to match this same dimension.
The second vertical barrier is capable similarly of reciprocating movement timed with that of the first barrier, inasmuch as when the first barrier is in a raised position and offered to the leading face of the selected group of bottles, the second barrier is in a retracted position, and vice-versa: thus, when a certain number of bottles has passed along the conveying surface and beyond the line of the first barrier, a group of bottles is separated initially from the continuous column waiting to advance, whereas the second barrier serves simply to distance the advancing groups one from the next as they are conveyed by the remaining branch of the intermediate station toward the separating station where the group is taken up by a push bar, guided by relative chains in such a way as to engage the selected bottles from the rear immediately beyond the downstream end of the pre-separating station.
In a second solution reflecting the prior art (see also Italian patent application BO94A 000160), the separating station is equipped with a conveyor belt positioned between the feed station and the selfsame separating station, capable of movement in the same direction as the feed direction and at a speed higher than the speed registering at the feed station.
The conveyor belt is driven intermittently thanks to a clutch mechanism that allows the drive to be engaged and disengaged according to predetermined pause and feed times, so that the bottles can be directed into the separating station as required to make up the selected group; the belt operates in conjunction with a top plate positioned to check the advancing front of the column of bottles during each pause.
The solutions briefly outlined betray drawbacks, however, attributable in the first case mentioned to the fact that the bottles are checked twice in succession, disallowing a high output per unit of time because of the mechanical limitations imposed by the reciprocating movement of the two barriers; also, the action of the barriers tends to increase the risk of the bottles being toppled, given the high throughput speeds at the various stations. In addition, the position of the second barrier must always be adjusted when changing from one size of group to another.
In the second case mentioned, one drawback is a possible lack of uniformity in the movement of the bottles on the conveyor belt; more exactly, should there be insufficient frictional contact generated by the belt during initial acceleration, or breaks in continuity of the columns of bottles advancing on the belt, the correct timing between the single columns of bottles can be lost. Such problems can therefore result in the line having to be stopped while the correct feed sequence of the groups is restored.
In both instances, moreover, the main drawback of the device is that of its constructional complexity overall.
Accordingly, the object of the present invention is principally to overcome the drawbacks mentioned above by embodying a device for the separation of continuously fed products into groups that will be structurally simple and allow a correct separation of the groups while maintaining a sizeable output per unit of time, at reasonable cost.
Another object of the invention is to provide a device for separating products into groups that can be adapted swiftly to handle products of different sizes, so that production need not be suspended for an unduly long interval when there is a changeover in production, for example, from the packaging of small cans to the packaging of large bottles.
Yet another object of the invention, finally, is to provide a device for the separation of products into groups that will enable easy selection of the number of products included in each group.
The stated objects are realized according to the invention in device for separating continuously fed products into groups, typically groups of bottles, comprising a conveyor belt, looped around a set of power driven pulleys and affording a horizontal top branch establishing a feed path along which to advance at least one column of bottles in a given direction and at a predetermined speed, positioned downstream of a feed station from which bottles are directed continuously along a predetermined feed direction coinciding with the conveying direction of the belt; also separator means operating in conjunction with the conveyor belt, by which the bottles are taken up from the feed station and ordered into groups before advancing toward other production line stations, incorporating at least one first flexible band looped around respective power driven pulleys and occupying a vertical plane, positioned alongside the conveyor belt and affording a horizontal top branch driven in the same direction as that of the conveyor belt at a first variable speed, and at least one second flexible band looped around respective power driven pulleys and occupying a vertical plane, positioned alongside the first flexible band and affording a horizontal top branch driven in the same direction as that of the conveyor belt at a second variable speed; and pluralities of first and second locating elements anchored to the first and second flexible bands, positionable orthogonally and adjacent to the conveyor belt when carried along the horizontal top branches of the respective flexible bands in such a way as to engage in contact with the bottles advancing on the belt.
Advantageously, the device further comprises a first and a second plurality of attachment devices associated respectively with the first and second flexible bands, by means of which the first and second locating elements can be anchored removably and in such a way as will allow of varying the number and mutual positioning of the selfsame first locating elements on the first flexible band, and the second locating elements on the second flexible band, according to the size of the bottles and the number of bottles making up the single group.